High speed switching device



March 1, 1960 K. E. SIHVONEN HIGH SPEED SWITCHING DEVICE Filed May 26, 1953 I!!! i 317 I 7! '58 \62 75 /0 6a 70 112) Qnbm.

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Arrow/gm Unite States Patent his 2,927,i?9 Patented Mar. i, 1966 HIGH SPEED SWITCHING DEVICE Kauno E. Sihvonen, Arcadia, Calif., assignor to Consolidated Electrodynamics Corporation, Pasadena, Calif., a corporation of California Application May 26, 1958, Serial No. 737,931

6 Claims. (Cl. 200-90) This invention relates to electromechanical devices for making and breaking electrical circuits, and more particularly is concerned with a device which can be used as a relay or as a chopper and operated at high make and break frequencies.

In copending application Serial No. 737,923, filed May 26, 1958, in the name of Herbert 1. Chambers, et al. and assigned to the assignee of the present invention, there is described a highspeed chopper in which the mechanical and electrical mass is made very small by means of a single conductive wire forming the moving element. This single moving wire is immersed in a permanent magnetic field, variations of current through the single wire,,causing it to be displaced in the magnetic field. Displacement of the wire is used to actuate contacts for making and breaking external circuits.

The present invention is an improvement on this type of relay device, and also utilizes the principle of a conductive wire immersed in a permanent magnetic field as the moving element of the relay. Displacement of the wire element in the field makes one set of contacts and breaks another set of contacts. By the improvement of the present invention, greater contact pressure is provided between the closed contacts, giving more positive switching action. This is accomplished without otherwise deterring the highspeed performance of the switching device.

In brief, the apparatus of the present invention com-' prises a bifilar element including a pair of parallel conductive wires with means for resiliently supporting the conductors under tension. The wires are immersed in a magnetic field formed by a permanent magnet. By passing a current through the parallel conductors in series, the conductors are deflected in opposite directions in response to the interaction of the current with the magnetic field. A contact arm extending between the parallel conductors and secured thereto normally engages a pair of spaced fixed contact elements. Displacement of the wires causes one set of contacts to open and the other set of contacts to be pressed together more firmly.

For a more complete understanding of the invention, reference should be had to the accompanying drawing, wherein:

Fig. 1 is a plan View, partially sectioned, ofthe relay; and r Fig. 2 is a sectional view taken substantially on the line 2-2 of Fig. 1.

Referring to the drawing in detail, the numeral indicates a base plate preferably constructed of insulating material, such as Bakelite. A bifilar wire element,

indicated generally at 16, including two parallel conductive portions 12 and 14 is constructed from a single fine wire. The ends of the wire are mounted by means of clamping lugs 18 and 20 projecting from the surface of the base plate 10. The clamping lugs are split and provided with clamping screws 22 and 24 respectively, by means of which the split halves of the lugs may be drawn securely together. The ends of the wire 16 are wedged between the split halves of the lugs and the screws 22 and 24 are tightened to grip the wire ends. The portions 12 and 14 are held in parallel relation by a cylindrical block 26 of insulating material around which the wire is looped. The block 26 is supported on the end of a cantilever spring 28. The cantilever spring 28 is anchored to the side of the base plate It as by means of a screw ftd. The cylindrical block 26 may be formed with a flat surface 32 below the wire loop to which the cantilever spring 28 is secured as by means of a screw 34. Tension on the wire 16 of the bifilar element is controlled by a stud screw 36 and engaging nut 38, the stud screw 36 extending through the cantiiever spring and being supported from the base plate 10.

The bifilar element is immersed in a permanent magnetic field formed by a pair of pole pieces 40 and 42. respectively having portions 44 and 46 projecting toward the portions 12 and 14 of the bifilar wire element 16. The projecting portions 44 and 46 of the pole pieces form pole faces which extend along a substantial portion of the length of the bifilar wire element 16. A block 48 of permanently magnetized material such as Alnico extends between the upper portions of the pole pieces 40 and 42, the pole pieces forming a low reluctance path for the magnetic flux whereby a strong field is formed between the projecting faces of the pole pieces in the region of the bifilar wire element.

If a current is passed through the bifilar wire element 16, as by connecting a potential source (not shown) between the lugs 18 and 20, the current will interact with the magnetic field to produce a transverse force on the parallel portions 12 and 14 of the bifilar wire element 16. This force will be in a vertical direction as viewed in Fig. 2. Since the current is in opposite directions in the two parallel portions, one portion will tend to move in the opposite direction from the other parallel portion. For example, as the'parallel portion 52 of the bifilar wire element 16 is displaced upward by the flow of current therethrough, the parallel portion 14 will be displaced downward. This mechanical displacement on the -bifilar wire element is used to operate contacts in the manner hereinafter described.

To this end, a pivot wire 50 is stretched between a pair of lugs 52 and 54 secured to the base plate 19. The pivot wire 59 is soldered or otherwise secured to the lug 52 and is clamped by the lug 54 which is split in the manner of the lugs 18 and 20 as described above. The lug 52 may be of spring material which maintains tension at all timeson the pivot wire 50. The pivot wire 50 is held between and parallel to the portions 12 and 14 of the bifilar wire element 16. A crossbar contact element 56 is secured at its center to the pivot wire 50, as by soldering or otherwise providing an electrical bond between the contact element 56 and the wire 50. The outer ends of the contact element 56 are wrapped around small insulating sleeves 58 and 60 through which pass the parallel portions 12 and 14 respectively of the bifilar wire element 16.

A pair of relatively fixed but adjustable contacts 62 and 64 normally engage the crossbar contact element 56 adjacent the ends thereof. Contacts 62 and 64 are mounted on the ends of cantilever spring supports 66 and 67 respectively, which are mounted to the base plate It} by means of screws 68 and 6% respectively. Adjustment of the contacts 62 and 64 is provided by means of adjusting screws 70 and 72 which threadedly engage members 74 and 76 mounted on the base plate by the same screws 68 and 69 respectively, as best shown in Fig. 2. The screws 70 and 72 bear against the lower side of the cantilever springs 66 and 67 respectively, whereby a turning adjustment of the screws 70 and 72 bends the associated cantilever springs to adjust the vertical position of the respective contacts 62 and 64.

In operation, it will be seen that the contacts 62 and 64 in effect act as pivots for the crossbar contact arm 56. Thus if the current passed through the bifilar wire element 16 is in a direction to displace the parallel portion 12 upwardly, the contact element 56 will pivot on the fixed contact 64. The corresponding downward movement of the parallel portion 14 of the bifilar wire element 16 will also cause the contact element 56 to pivot about the fixed contact 64. This pivotal movement about the fixed contacts means that the pivot wire 50 is displaced upwardly. Since the wire 50 is under tension, this upward displacement produces a restoring force which is translated to the closed contacts thereby increasing the contact pressure.

A low reluctance magnetic flux path is provided in the region between the parallel portions 12 and 14 of the bifilar wire element 16 by means of a pair of high permeability blocks 78 and 80 located on either side of the crossbar contact element 56 and secured to the lower plate 10. The blocks 73 and 80 are provided with aligned slots for receiving the pivot wire 50. After assembly the slots are partially bridged magnetically by a low reluctance insert element 82 having a projecting portion that fits down into the grooves in the blocks 78 and 80. Clearance is provided below the insert member 82 for movement of the pivot wire 50. In this manner actually two flux gaps are formed adjacent the projecting portions 44 and 46 of the pole pieces for concentrating the magnetic field in the gaps in the region of the parallel portions 12 and 14 of the bifilar wire element 16.

From the above description it will be recognized that a circuit breaking device is provided which may be used either as a relay by switching current on and off through the bifilar wire element 16, or which may be used as a chopper by passing an alternating current through the bifilar wire element 16. Since the moving mass of the device is extremely small, its time response can be made very large. Moreover, the equivalent electrical mass is very small since the inductance of the bifilar wire element 16 is negligible. The resonance point of the oscillating system can be made well above several thousand cycles, so that the device can be operated as a chopper at frequencies well below resonance and still be as high as several thousand cycles per second. Contact noise is substantially reduced by the increased contact pressures which are possible due to the action of the bifilar wire element.

What is claimed is:

l. A switching device comprising a frame member including a pair of spaced projecting lugs, a pivot wire cxtcnding between and secured to the lugs, a contact arm secured to the wire intermediate the lugs, a bifilar conductive element, means for supporting the bifilar element from the frame member with two portions thereof parallel to and positioned respectively on either side of the pivot wire, the contact arm being insulatedly secured at either end to the bifilar element at the respective parallel portions thereof, magnet means secured to the frame member, the magnet means including pole faces that extend the length of the parallel portions of the bifilar element, whereby the bifilar element is immersed in a magnetic field, a pair of contacts insulatedly supported from the frame member on either side of the pivot wire and normally in contact with the contact arm, and means for passing current through the bifilar element in either direction to thereby cause the bifilar element to be displaced by the interaction with the magnetic field and move the contact arm out of engagement with one of said contacts.

2. A switching device comprising a frame member, a contact arm, a bifilar conductive element, means for supporting the bifilar element from the frame member with two portions thereof parallel to each other, the contact arm being insulatedly secured at either end to the bifilar element at the respective parallel portions there of, magnet means secured to the frame member, the magnet means including pole faces that extend along the parallel portions of the bifilar element, whereby the bifilar element is immersed in a magnetic field substantially perpendicular to a portion of the lines of fiux therein, a pair of contacts insulatedly supported from the frame member and positioned adjacent opposite ends of the contact arm for making contact therewith, and means for passing current through the bifilar element in either direction to thereby cause the bifilar element to be displaced by the interaction with the magnetic field and move the contact arm out of engagement with one of said contacts.

3. A switching device comprising a frame member, a contact arm, a bifilar conductive element, means for sup porting the bifilar element from the frame member with two portions thereof parallel to each other, the contact arm being insulatedly secured at either end to the bifilar element at the respective parallel portions thereof, magnet means secured to the frame member, the magnet means including pole faces that extend along the parallel portions of the bifilar element, whereby the bifilar element is immersed in a magnetic field substantially perpendicular to a portion of the lines of flux therein, and a pair of contacts insulatedly supported from the frame member and positioned adjacent opposite ends of the contact arm for making contact therewith.

4. Switching apparatus comprising a pair of parallel conductors, means for resiliently supporting the conductors under tension, means for connecting the conductors electrically in series at adjacent ends, whereby a current can flow in opposite directions in the two conductors, means for producing a magnetic field in which a portion of the lines of flux extend perpendicular to the pair of parallel conductors, the conductors being positioned in said field, a contact arm extending between the two parallel conductors and secured to said conductors, a pair of spaced fixed contactor elements positioned to respectively contact said contactor arm with lateral displacement of the parallel conductors in a direction perpendicular to the plane defined by the pair of parallel conductors, and means for passing an alternating current through the series connected conductors to impart an oscillating movement to said conductors and the associated contact arm.

5. Switching apparatus comprising a pair of parallel conductors, means for resiliently supporting the conductors under tension, means for connecting the conductors electrically in series at adjacent ends, whereby a current can How in opposite directions in the two conductors, means for producing a magnetic field in which a portion of the lines of flux extend perpendicular to the pair of parallel conductors, the conductors being positioned in said field, a contact arm extending between the two parallel conductors and secured to said conductors, and. a pair of spaced fixed contactor elements positioned to respectively contact said contactor arm with lateral displacement of the parallel conductors in a direction perpendicular to the plane defined by the pair of parallel conductors.

6. Switching apparatus comprising a pair of parallel conductors, means for resiliently supporting the conductors under tension, means for passing a current in opposite directions in the two conductors, means for producing a magnetic field in which a portion of the flux extends perpendicular to the pair of parallel conductors, the conductors being positioned in said field, a contact arm extending between the two parallel conductors and secured to said conductors, and a pair of spaced fixed References Cited in the file of this patent UNITED STATES PATENTS 986,039 Bachelet Mar. 7, 1911 10 2,381,309 Powell Aug. 7, 1945 2,570,315 Brewer Oct. 9, 1951 

